Sprayer Looking for a Chemical Injector

[TheFarmerInAdell]

I'm looking to add an in-line chemical injector to my 3 point sprayer. The pump is PTO run, and I have 6 nozzles on it. I typically use the yellow or red nozzles (.2gpm or .4gpm), so the total flow is somewhat low. I don't like having the chemicals in the tank as I want to use it for just about everything. I would like to have just water in the tank and have the the chemicals (herbicides, pesticides, whatever else) be injected into the line just before the nozzles. I'd like to be able to spray the weeds in the hay field, then water the garden with the hand held hose and not worry about residual chemicals in the tank killing my tomatoes. I haven't had any luck finding an injector to fit my needs.

Does anyone have any suggestions?

 

[M59]

TheFarmerinADell,

A nice objective but also one fraught with problems.

The ratio of chemical to water ( diluent ) for many chemicals, particularly insecticides can be very low and depends upon the chemicals original solution strength. I have a few that are 1-2 grams per gallon of water.

At very low flow rates ( the 0.2-0.4 are very low flow ) the calibration of injection rate becomes problematic as very small changes of injected quantity into a very low flow system are actually large swings in the ratio of chemical to diluent ( water ).
You would need peristaltic pump or some other positive displacement pump since gravity feed is highly error prone.

How do you calibrate such a system before each use?

How do you assure chemical isn't flowing into the water while you are not spraying?

What happens to the chemical that has flowed into the water in pipe leading to spray heads before water leaves the spray head and you stop spraying? Does water and chemical flow back into the water holding tank?

To solve some of the above problems, you would have to add the chemical just post the nozzle end into the water as it sprays out. Similar to metal arc spraying in the metal finishing trade or some versions of epoxy layup for boat building where the two reactive epoxy components mix in the spray head but the epoxy sprayers also have method to air blow out residual epoxy components so they don't mix, at time of shutdown, and clog sprayer.

I'm interested to see what solutions are suggested.

 

[Hay Dude]

I'm looking to add an in-line chemical injector to my 3 point sprayer. The pump is PTO run, and I have 6 nozzles on it. I typically use the yellow or red nozzles (.2gpm or .4gpm), so the total flow is somewhat low. I don't like having the chemicals in the tank as I want to use it for just about everything. I would like to have just water in the tank and have the the chemicals (herbicides, pesticides, whatever else) be injected into the line just before the nozzles. I'd like to be able to spray the weeds in the hay field, then water the garden with the hand held hose and not worry about residual chemicals in the tank killing my tomatoes. I haven't had any luck finding an injector to fit my needs.

Does anyone have any suggestions?

Have you contacted Paul B Hardware? They have everything under the sun for sprayers.
Not far from me. Amazing place!

Sprayers & Applicators - Agriculture Supplies

paulbhardware.com

 

[Wagtail]

The first thing that comes to mind is a type of 'venturi' device/system.

 

[K5lwq]

Could you make something like this work? You can put different size tips in to meter how much chemicals you want per gal. This happens to be a air gap version but I should have some older action gap back flow versions. I should have two GPM as well. One of them is 1gal/minute the other would be 4gal/minute.

 

[TheFarmerInAdell]

TheFarmerinADell,

A nice objective but also one fraught with problems.

The ratio of chemical to water ( diluent ) for many chemicals, particularly insecticides can be very low and depends upon the chemicals original solution strength. I have a few that are 1-2 grams per gallon of water.

At very low flow rates ( the 0.2-0.4 are very low flow ) the calibration of injection rate becomes problematic as very small changes of injected quantity into a very low flow system are actually large swings in the ratio of chemical to diluent ( water ).
You would need peristaltic pump or some other positive displacement pump since gravity feed is highly error prone.

How do you calibrate such a system before each use?

How do you assure chemical isn't flowing into the water while you are not spraying?

What happens to the chemical that has flowed into the water in pipe leading to spray heads before water leaves the spray head and you stop spraying? Does water and chemical flow back into the water holding tank?

To solve some of the above problems, you would have to add the chemical just post the nozzle end into the water as it sprays out. Similar to metal arc spraying in the metal finishing trade or some versions of epoxy layup for boat building where the two reactive epoxy components mix in the spray head but the epoxy sprayers also have method to air blow out residual epoxy components so they don't mix, at time of shutdown, and clog sprayer.

I'm interested to see what solutions are suggested.

I use lower flow nozzles so I can cover more ground on a single tank. I use a 150 gallon tank to spray about 4 acres and I mix chemicals based on acreage not based on volume of water. I get a total of 1.2-2.4 total gpm with the nozzles I use. I use a PTO driven roller pump and I would put the injector after the pump and between the pressure relief valve and the nozzles. To stop spraying I turn the PTO off so with no water flowing there should be no chemical flowing. There are pressure activated check valves at the nozzles to prevent siphon dripping and back-feeding.

Have you contacted Paul B Hardware? They have everything under the sun for sprayers.
Not far from me. Amazing place!

Sprayers & Applicators - Agriculture Supplies

paulbhardware.com

I looked around there, but I didn't see anything that would be for injecting the chemicals.

The first thing that comes to mind is a type of 'venturi' device/system.

That's what I've been looking for, but I haven't found one yet. Most venturi devices require a minimum of 2gpm. Depending on my nozzle I am between 1.2gpm and 2.4gpm.

Could you make something like this work? You can put different size tips in to meter how much chemicals you want per gal. This happens to be a air gap version but I should have some older action gap back flow versions. I should have two GPM as well. One of them is 1gal/minute the other would be 4gal/minute.

View attachment 754903

I had to look that up because I had no idea what that was. That seems to be on the right track of what I'm looking for. I'll dig around based on that device and see what I can find. Thanks for the tip!

 

[K5lwq]

I had to look that up because I had no idea what that was. That seems to be on the right track of what I'm looking for. I'll dig around based on that device and see what I can find. Thanks for the tip!

I have some I will send you if you want to try it. Just PM me you address.

 

[TheFarmerInAdell]

I have some I will send you if you want to try it. Just PM me you address.

Thanks! PM sent.

 

[JDW2]

I don't know if this is big enough but it's working action is what you're looking for I think. One tank for water, one tank for chemical and then they mix in the line.

https://www.tractorsupply.com/tsc/product/chapin-97761-the-first-ever-clean-tank-tow-behind-with-boom-97761

 

[TheFarmerInAdell]

I don't know if this is big enough but it's working action is what you're looking for I think. One tank for water, one tank for chemical and then they mix in the line.

https://www.tractorsupply.com/tsc/product/chapin-97761-the-first-ever-clean-tank-tow-behind-with-boom-97761

That's exactly what I'm trying to accomplish. Sometime between last night and this morning that item disappeared. I did find another one that isn't the tow-behind: https://www.tractorsupply.com/tsc/p...-25-gal-atv-mixes-on-exit-97562?cm_vc=-10011#

I went to the Chapin website to do some more digging. After further investigation, it appears that the unit mixes the chemical right before the pump. The way it mixes isn't venturi, but with the low pressure (vacuum) on the inlet side it will draw water and concentrate in. I will need to mix after the pump and pressure relief valve, because the pressure relief valve will flow the mixture back into the tank if I mix before the pump.